Hi Christophe,
Thanks a lot for your answer. Is exactly what I was looking for. I will try it.
By the way, I found a little trick to know if a VM has a snapshot. Even when the method is not exposed by the plugin, is still present in the XML. So, if you have a VM in a workflow, you can get the xml with .toXml() and check for the XML Element.
Regards,
Damián.